Hypernatremia

explain hydrostatic pressure of arterials vs mid capillary vs venules

arterials: capillary hydrostatic pressure higher → pushes the blood out of the artery

mid: equal so no net movement

venules: capillary hydrostatic pressure is less than blood colloidal osmotic pressure → pushes blood in to the vein

Describe the physiologic response to rising plasma osmolality in a normal individual in terms of ADH release and thirst?

increased ADH

increased thirst

ADH aka ____ is made in the ___ and released from the ____

aka vasopressin

made in the hypothalamus

released from the pituitary gland

3. ADH exerts its effect on principal cells of the collecting duct through what mechanism?

Activating V2 receptors → ↑ cAMP → insertion of aquaporin-2 channels 

hypernatremia is when the plasma sodium concentration is ___

>145 mmol/L

hypernatremia is more or less common than hyponatremia?

what is the mortality rate?

less common

40-60% (hella high)

Hypernatremia is usually the result of one of three main situations: 

impaired water intake

hyperglycemic hyperosmolar state

diabetes insipidus

What are the two common age demographics for hypernatremia?

infants and elderly (especially with severe dementia)

how does hyperglycemia play a role in hypernatremia

the glucose draws water from the ICF to the ECF which dilutes the sodium concentration

What are 4 common findings with dehydration?

tachycardia, orthostatic hypotension, dry mucous membranes, and decreased skin turgor

What are 3 common clinical findings with hypernatremia?

depressed sensorium, focal deficits, and seizures

What do we suspect with a high urine osmolality (>600) (aka concentrated urine), increased BUN, increased creatinine, and normal glucose levels?

inadequate water consumption (lack of free water intake)

What do we expect if we see markedly elevated serum glucose?

hyperglycemia

What do we expect with a low urine osmolality (<600) (aka dilute urine)?

diabetes insipidus

What is the goal for reducing serum sodium?

reduce it by 4-6 meq/L not exceeding 10 meq/L in 24 hours

What do we suspect if we see high plasma sodium concentration, increased plasma osmolality, and low urine osmolality?

diabetes insipidus

What are the two types of diabetes insipidus? describe them briefly

central: lack of ADH

nephrogenic: kidney issue (lithium is a common cause)

Which type of diabetes insipidus?

idiopathic, head trauma, postoperative, CNS tumors, basilar meningitis, etc.

central 

Which type of diabetes insipidus?

lithium, amphotericin B, cidofovir (HIV med), amyloidosis, sarcoidosis, lupus, etc.

nephrogenic

How do we tell if diabetes insipidus is central or nephrogenic?

forst fluid restrict the pt

then admin desmopressin (synthetic ADH/vasopressin)

central: urine osm more then doubles

• because that was the issue… lack of ADH

nephrogenic: urine osm unchanged

• because they have normal ADH levels… their kidney is fucked up/being fucked up

How do we treat central diabetes insipidus?

desmopressin (synthetic ADH)

How do we treat nephrogenic diabetes insipidus?

if possible d/c offending agent, low sodium and low protein diet, thiazide diuretics, amiloride for pts taking lithium